8 Partitioning JSON Data
You can partition a table using a JSON virtual column as the partitioning
key. The virtual column is extracted from a JSON column using SQL/JSON function
json_value
.
Partition on a Non-JSON Column When Possible
You can partition a table using a JSON virtual column, but it is
generally preferable to use a non-JSON column. A partitioning key specifies which
partition a new row is inserted into. A partitioning key defined as a JSON virtual
column uses SQL/JSON function json_value
, and the
partition-defining json_value
expression is evaluated each time
a row is inserted. This can be costly, especially for insertion of large
JSON documents.
Rules for Partitioning a Table Using a JSON Virtual Column
-
The virtual column that serves as the partitioning key must be defined using SQL/JSON function
json_value
. -
The data type of the virtual column is defined by the
RETURNING
clause used for thejson_value
expression. -
The
json_value
path used to extract the data for the virtual column must not contain any predicates. (The path must be streamable.) -
The JSON column referenced by the expression that defines the virtual column can have an
is json
check constraint, but it need not have such a constraint.
See Also:
Oracle Database SQL
Language Reference for information about CREATE
TABLE
Example 8-1 Creating a Partitioned Table Using a JSON Virtual Column
This example creates table j_purchaseorder_partitioned
, which is partitioned using virtual column po_num_vc
. That virtual column references JSON column po_document
(which uses CLOB
storage). The json_value
expression that defines the virtual column extracts JSON field PONumber
from po_document
as a number.
CREATE TABLE j_purchaseorder_partitioned
(id VARCHAR2 (32) NOT NULL PRIMARY KEY,
date_loaded TIMESTAMP (6) WITH TIME ZONE,
po_document JSON,
po_num_vc NUMBER GENERATED ALWAYS AS
(json_value (po_document, '$.PONumber' RETURNING NUMBER)))
PARTITION BY RANGE (po_num_vc)
(PARTITION p1 VALUES LESS THAN (1000),
PARTITION p2 VALUES LESS THAN (2000));
Parent topic: Store and Manage JSON Data